Mass spectrometry apparatus are known in the art. For example, U.S. Pat. No. 5,468,452 discloses a quantitative analysis combining high performance liquid chromatograph and mass spectrometry.
In accordance with the patent, quantitative analysis of organic compounds is carried out using a high performance liquid chromatograph which is linked to the mass spectrometer by an atmospheric pressure chemical ionization interface which includes an ionization chamber having a corona discharge electrode formed of a silver or platinum alloy, stainless steel or tinned or non-plated iron. Hagiwara however, does not disclose the use of a reacting gas including fluorine.
U.S. Pat. No. 4,933,548 discloses a method and device for introducing samples for a mass spectrometer. Boyer et al discloses a technique and device for introducing microsamples in the ionization source of a mass spectrometer which heats the microsample and feeds an adjustable flow of reagent for transforming the microsample into a gaseous compound. The disclosed system basically performs a chemical reaction interface (CRI). The reactant gas may include fluorine. When the temperature increases beyond the sublimation point of the metal oxide and reaches the sublimation point of hexaf luorine, feeding of the ion source is begun by opening the valve which feeds the ion source 18 of the spectrometer. The isotopic ratio measurements may be compared with those of standard uranium, hexaf luorine admitted to the spectrometer. However, Boyer does not disclose microwave heating and hence lacks any teaching of a continuous sample flow. Also, Boyer does not utilize an IRMS and accordingly, is incapable of obtaining the quality of results obtainable with the present invention.
U.S. Pat. No. 4,633,082 discloses a process for measuring degradation of sulfur hexafluoride in high voltage systems. Sauers discloses the use of fluorine as a carrier gas.
U.S. Pat. No. 5,086,225 discloses a thermal cycle recirculating pump for isotope purification. The patent discloses the use of fluorine as a carrier gas.
Song and Abramson, J. Am. Soc. Mass Spectrom. 1995, No. 6, p, 421-427 describes the use of nitrogen trifluoride as a new reactant gas in chemical reaction interface mass spectrometry for detection of phosphorus, deuterium, chlorine and sulfur. The paper does not disclose or suggest the use of fluorine gas to obtain mass spectrometer resolution between samples which contain carbon and nitrogen.
There is a need in the art of sensitive mass spectrometers and assays which provide mass spectrometer resolution between carbon and nitrogen compounds. When mass spectrometry is performed as is done with most spectrometers, in the presence of oxygen, the mass of carbon and nitrogen containing compounds both overlap around 28, 29 m/z. The present invention overcomes deficiencies of prior art apparatus and methods through their ability to separate overlapping signals with the use of fluorine gas.